Comments about the book "Physics & Philosophy" by Werner Heisenberg

This document contains comments about the book: "Physics & Philosophy" by Werner Heisenberg. Penguin Books 1958

• The text in italics is copied from that url
  
• Immediate followed by some comments
  

In the last paragraph I explain my own opinion.

Contents

• Introduction - page 1
• 1. An Old and a New Tradition - page 15
• 2. The History of Quantum Theory - page 18
• 3. The Copenhagen Interpretation of Quantum Theory - page 32
• 4. Quantum Theory and the Roots of Atomic Science - page 47
• 6. The relation of Quantum Theory to Other Parts of Natural Science - page 81

Reflection

• Reflection 1 -
• Reflection 2 -

Introduction Page 1

The first was a theory of space, time and motion, called realtivity

Okay

The author of this book played a leading role in the early formulation of quantum mechanics and in the subsequent clarification of its revolutionary implications.
Those readers who know anything at all of quantum mechanics will know anything at allof quantum mechanics will know that the famous 'uncertainty principle' a key component in quantum physics, is named after Heisenberg

Okay

Page 2

Thus questions about space and time, or the qualities of material objects such as their positions, which seem entirely reasonable in everyday discourse, cannot always be meaningfull answered.

This requires an explanation.

True, relativity contains some strange ides, such as time dilation and length contraction, curved space and black holes.

Current understanding IMO should consider black holes as a special type of stars, which don't emit light, to the outside world.

It also asserts that certain types of question, which sound perfectly reasonable and meaning ful, have no unambigious answer.
To ask, for example , at what time an event occurs, or whether two events that are separated in space occur at the same moment, may not be answerable as the questions stand because the theory tells us that there is no universable time, nor is there a universable concept of simulataneity.

This requires a definition of what means the same moment, universable time and simulataneity.

Page 4

At the heart 0f the quantum revolution is Heisenberg's uncertainty principly

This requires a detailed a deep study what this physical means.

This tells us, roughly speaking that all physical quantities that can be observed are subject to unpredicatable fluctuations, so that their values are not precisely defined.

I expect that most physical quantities can not precisely be observed. That means this is a measurement issue and not directly a physical issue.

Consider, for example, the position x and the momentum p (p=m*v) of a quantum particle such as an electron.

Page 16

For such reasons it may not be un important task to try to discuss these ideas of modern physics in a not too technical language, to study their phylosophical consequences, and to compare them with some of the older traditions.

It is better to use the wording 'latest developments' instead of modern physics.

The best way to enter into the problems of modern physics may be by a historical description of quantum theory.

A better description would be: 'The best way to describe the latest developments, would be a historical description of quantum theory.'

The enormous and extremely complicated experimental equipment needed for reasearch in nuclear physics shows etc.

This complicated equipment has to be explained.

Therefore, the radiation emitted by such a black body at high temperatatures is a suitable object for physical research; it is a simple phenomenon that should find a simple explanation in terms of known laws for radiation and heat.

The word simple should not be used (?). In general physical phenomena should not be explained with existing laws.

The attempts made at the end of the ninteenth century by Lord Rayleigh and Jeans failed, however, and revealed serious difficulties.

Such a result is not what we should expect.

This turning did not remove any of the difficulties inherent in the problem, but it simplified the interpretations of the empirical facts.

This conclusion is not clear.

Page 20

For a better understanding of this paradox it is useful to compare the procedure for the theoretical interpretation of an experiment in classical physics and in quantum theory.

Okay

In Newton's mechanics, for instance, we may start by measuring the position and the velocity of the planet whose motion we are going to study.

A more practical method is to measure the position and the time, twice. (or more at regular intervals). The velocity can than be calculated.

The result of the observation is translated into mathematics by deriving numbers for the coordinates and the momenta of the planet from the observations.

To calculate the mass of the planets based on observations requires to use Newton's mechanics and is not simple. The accuracy is a function of the observations.

Page 33

The idea of the smallest, indivisible ultimate building blocks of matter first came up in connection with the eleboration of the concepts of Matter, Being and Becoming which characterized the first epoch of Greek philosophy.

Okay

Page 16

The system of definitions and axioms which can be written in a set of mathematical equations is considered as describing an eternal (physical nv) structure of nature, depending neither on a particular space nor on partical time.

To be demonstrated by means of experiments.

Page 83

This change led back to a point of view which had been held by many scientists before Newton.
An action could so it seemed be transferred from one body to an other only when two bodies touched each other; for instance, in a collision or through friction.
Newton had introduced a very new and strange hypothesis by assuming a force that acted over a long distance

That is a very important 'observation'
This requires finally an experiment that demonstrates this. See ?

Now in the theory of fields of force one could come back to the older idea, that action is transferred from one point to a neighboring point, only by describing the behaviour of the fields in terms of differential equations.

Such a description is mathematical correct but physical of 'no importance'. The importance lies in the underlying physical reality.

Page 84

Under the impression of this completely new situation many physicists came to the following somewhat rash conclusion: Newtonian mechanics had finally been disproved.

This conclusion requires more reasoning.

The primary reality is the field and not the body, and the structure of space and time is correctly describedby the formulas of Lorentz and Einsteins and not by the axioms of Newtons.

This is doubtfull. IMO the Lorentz formulas describe mathematical the behaviour of time as measured by a physical clock. Physical time, the time that all humans feel in the universe, expressed as universal time, cannot be catched in a mathematical equation.
However all this reasoning is very interesting.

To be continued.

Reflection 1

Reflection 2

Reflection 3

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